This application claims the priority of New Zealand patent application no. 286543, filed May 8, 1996, and New Zealand patent application no. 299570, filed Oct. 11, 1996, which are incorporated herein by reference.
The present invention comprises a diaphragm valve, particularly suitable for irrigation applications.
Diaphragm valves of various types are used in various applications. Various designs and constructions for such diaphragm valves are known, which are generally relatively complicated multipart valves.
The present invention provides an improved or at least alternative form of diaphragm valve.
In broad terms the invention comprises a diaphragm valve comprising a hollow body having an outlet port to connect a hydraulic or pneumatic system to the interior of the body of the valve and at least one inlet port to the interior of the body of the valve, and a diaphragm movably mounted within the interior of the body and normally closing said outlet port with a cavity behind the diaphragm and a bleed aperture through the diaphragm from said outlet port into the cavity behind the diaphragm, such that when the pressure on the outlet side of the diaphragm falls below the pressure on the inlet side of the diaphragm, the diaphragm will move away from the outlet port to open the port to fluid entering the interior of the body of the valve through the inlet port(s) and will move to close the outlet port when the pressure on the outlet side of the diaphragm is equalized with the pressure on the inlet port side of the diaphragm.
Preferably the diaphragm component includes a thin flexible annular skirt extending from the periphery of the diaphragm with the distal edge of the skirt retained in an annular recess around the cavity behind the diaphragm to movably mount the diaphragm within the interior of the body so that the diaphragm moves by flexing and/or folding of the skirt.
Preferably the skirt is integrally formed with a major part of the body of the diaphragm by injection moulding from a plastics material.
The diaphragm valve of the invention is of a simple and robust construction and may be formed entirely from plastic moulded components, although parts of the diaphragm valve of the invention may also be formed from metal by casting for example, particularly for larger sizes of valves of the invention.
Diaphragm valves of the invention are particularly suitable for use in irrigation systems or similar where water is drawn from a reservoir or stream. The valves of the invention will give reliable long term performance in such demanding applications. The valves of the invention are suitable for other applications also however, and are not limited to irrigation or like applications.